The effectiveness of media promotions and corresponding advertising rates were strongly influenced by the size and scope of the potential audience which could be reached by that format.
With regard to outdoor billboard advertising, it had been extremely difficult within the industry to sample or otherwise predict prospective viewer response since there was no way of quantitatively measuring when an advertising display was observed and the frequency of such observations. A further difficulty in accumulating such data resulted because those outdoor displays were placed along highways having fast-moving vehicular traffic.
Prior attempts to collect and record information regarding audience exposure to billboard advertising employed such devices as a pressure sensitive tape placed across the roadway which functioned as a counter and thus indicated traffic flow or density. That system, however, merely provided numerical data relative to the number of vehicles but failed to take into consideration whether the occupants within the vehicles observed the roadside display.
Another monitoring arrangement utilized concealed cameras that were mounted behind or in close proximity to the billboard and were aimed at the passing automobiles. A distinct shortcoming of that system was that it was based upon the recording and counting of those occupants within the vehicles that were facing in the direction of the billboard. That concept relied upon head movement toward the display as an indication of viewer observation of the display. It should be apparent that that survey method failed to appreciate that a subject viewer did not necessarily need to turn one's head in order to view the roadside display especially if the billboard was visible at some distance along the highway and conversely head movement in the direction of the billboard was not an absolute indicator that the individual was looking at the billboard. Furthermore, tinted automobile windows and the usual accumulation of dirt severely interfered with the ability to observe the occupants. This was also compounded during nighttime when visibility within the automobile was drastically limited and during hazy weather conditions.
Another disadvantage of the previous survey methods was that they could not provide accurate data regarding spectator perception because there was no way of determining when the viewer's line of sight was directed at the advertisement.
Although the utilization of radiant energy for monitoring eye movement was shown in U.S. Pat. Nos. 3,379,885 and 3,450,446, those devices were not directed to media survey methods using thermal imagery as in the present invention. Additional U.S. patents which disclosed apparatus relying upon eye reflected light include U.S. Pat. Nos. 4,034,401, 3,986,030 and 3,712,716. It should be noted that those last mentioned devices were not concerned with sensing eye movement from a subject in relative motion.